The U.S. government has a special committee to think of each situation that could cause a break-down of society and government and think of a plan to be carried out during that time to prevent that. They have whole binders of plans ranging from nuclear war to a zombie apocalypse.

Yes, if you have read World War Z by max brooks, their plan is very similar to to Rediger (that guy from south africa) plan.
Basically supply small pockets of america and retreat the government to a naturally safe place and re-organize.
They also have contingencies for vampires, nukes, demons, magic and various other "silly" things.